Continuously operating press apparatus



April 23, 1963 A. J. A. ASPLUND 3, 8

CONTINUOUSLY OPERATING PRESS APPARATUS Filed March 18, 1960 5Sheets-Sheet 1 Fig.1

April 23, 1963 A. J. A. ASPLUND CONTINUOUSLY OPERATING PRESS APPARATUSFiled March 18, 1960 5 Sheets-Sheet 2 I mvgnmm drnegE/hn April 23, 1963A. J. A. ASPLUND counuuousu OPERATING PRESS APPARATUS 5 Sheets-Sheet 3Filed March 18,

Fig.3

INVENTOR.

drrae/ (lb/gm drif A ril 23, 1963 A. .1. A. ASPLUND 3,086,454

CONTINUOUSLY OPERATING PRESS APPARATUS Filed March 18, 1960 5Sheets-Sheet 4 Fig. A

INVENTOR.

April 1963 A. J. A. ASPLUND 3,086,454

CONTINUOUSLY OPERATING PRESS APPARATUS Filed March 18, 1960 5Sheets-Sheet 5 INVENTOR. dme Jaigm drZ/zu ds vlzzm' tates 3,036,454CONTINUOUSLY OPERATING PRESS APPARATUS Arne Johan Arthur Asplund, 11Orevagen, Bromrna, Sweden Filed Mar. 18, 1960, Ser. No. 15,950 Claimspriority, application Sweden Mar. 23, 1959 4 Claims. (l. 100-121)obtained in breweries. The invention may also be used in the recovery ofpressing of cane juice in the production of sugar.

The product desired to be recovered by the pressing operation may beconstituted of either the liquid or the suspended solid material or boththe liquid and the material. This last-mentioned result is desired, forexample, in the production of chemical or semi-chemical cellulose pulpwherein a suspension of fibers in water is formed which water alsocontains valuable chemicals. After separation of the two components saidchemicals are recovered by an evaporation process.

It is known in prior art to build a press of the kind in considerationhaving an interspace confined by two rotatable pressing members anddiminishing in size in the direction of rotation so as to cause thesuspension of material to be subjected to a gradually increasingpressure While the liquid is expelled through screen portions formed inone or the other or both press members.

One primary object of the invention is to provide a press apparatus ofthe type in consideration which is simpler and consequently cheaper toconstruct than those hitherto known.

A further object of the invention is to provide a press apparatusrendering it possible to exert a highly uniform pressure on the materialto be dried. Still a further object of the invention is to provide apress apparatus permitting operation with high pressures and having highcapacity.

According to a main feature of the invention one of the rotatable pressmembers is mounted eccentrically within the other rotatable press memberin such a manner as to form an interspace between said members having acrescent-shaped cross-section. In a structure with horizontal shafts theshaft of the inner press member is displaced eccentrically in relationto the shaft of the outer press member and also in relation to thedirection of relative rotation in such a manner as to cause the minimuminterspace or the nip to be located above the horizontal plane throughthe first-mentioned shaft and on that side of the apparatus Where themembers during rotation are moving upwards. Preferably, the two pressmembers are radially displaceable relatively to one another in order toallow adjustment of the magnitude of the nip, and suitably the directionof the displacement is horizontal.

Further objects and advantages of the invention will become apparentfrom the following description, considered in connection with theaccompanying drawings which form part of this specification and ofwhich:

atent line I-I of FIG. 3 through a press apparatus constructed accordingto the invention and intended for separation of suspended pulp and aliquid containing chemicals from one another.

FIG. 2 is a cross-sectional view following line II-II of FIG. 1.

FIG. 3 is an end elevation of the press apparatus seen from the right tothe left of FIG. 1, some parts of the apparatus being shown in sectiontaken on line III-III of said figure.

FIG. 4 is a diagrammatic and part-sectional view of a device foradjustment of the position of the inner press member.

FIG. 5 is a sectional view similar to that shown in FIG. 2 through apress apparatus constructed according to a slightly modified embodimentof the invention.

Referring to the drawings, reference numeral 10 denotes a casing orframe of a press enclosing two substantially cylindrical press membersgenerally denoted by 12 and 14, respectively. The inner member 12 willhereinafter be designated as the cylinder 12 and the outer member 14 asthe drum 14. The cylinder '12 is rigidly connected with centrallymounted journals 16 and 18, respectively, carrying bearings denoted by20 and 21, respectively. The drum 14 is supported externally bypreferably three pairs of rolls 22, 24 and 26 adapted to co-operate withtwo bearing rings 28 shrunk on the external surface of the drum. Therolls are in pairs carried on shafts 29, 30

and 31 mounted in bearings 32 secured to the frame 10.

The cylinder 12 is mounted radially inside the drum 14, the mounting ofboth said parts being carried out in such a manner as to position theiraxes ecceutrically relatively to one another. They are driven to rotatein the same direction counter-clockwise according to the arrow 24 inFIGS. 2 and 5 with the same or possibly slightly different speeds oftheir circumferential screen surfaces which speed may be a fewrevolutions per minute. During this movement the spacing between twoopposite points on their cylindrical surfaces varies and attains amaximum value at the so-calledgap indicated at 36 in FIGS. 2 and 5 and aminimum value at a diametrically opposite point the so-called nip 38.From a power source (not shown) a transmission member formed in theembodiment shown as a chain 40 passes over a sprocket 42 rigidly securedto the shaft 30 of the rolls 24. Between said sprocket and anothersprocket 44 carried on the shaft 38 of the upper pair of rolls 26 achain 46 passes so that two of the three pairs of rolls in theillustrated embodiments are driven. The cylinder 12 is suitably drivenfrom the same power source as the drum by means of a chain 48 passingover a sprocket 50 carried on a shaft 52 which in turn is mounted in theframe 10. Secured to the shaft '52 is a furtherspro'cket 54 which bymeans of a chain 58 is in driving connection with a sprocket 56 rigidlysecured onto the journal 16 of the cylinder 12. The sprocket 50 ispreferably located vertically below the center of the larger sprocket56.

The relation between the gap 36 and the nip 38 is variable due to meansbeing provided to displace the parts 12 and 14 relatively to oneanother. In the embodiments shown the cylinder 12 is displaceablehorizontally within the frame 10. Said frame is on each side providedwith an aperture bounded at its top and its base by straight guides 60or a cover 62 provided on said guides and made of a material withsuitable gliding properties such :as Teflon. Blocks 64, 65 are mountedwith their inner surface on the external ring of the bearings 20 and 21,respectively, and they are on their outer surface provided with straightguide faces intended for co-operation with the guides 60, 62. Providedon either side of both bearings and the guide members are covers 66, 68having a rectangular outer contour. The horizontal displacement of thecylinder 12 is effected by hydraulic power in a manner which shall bedescribed more in detail further below in this specification.

The interspace 69, the cross-section of which is crescentshaped andwhich viewed in the direction of rotation extends from adjacent the gap36 to the nip 38 between the cylinder 12 and the drum 14 is laterallyclosed by stationary shield plates 70. Said shield plates are sealedtowards the suitably fiat lateral end faces of the cylinder and the drumby sealing members 72 and 74, respectively, and are adjusted relativelyto said sealing members by means of screws 76. It is of substantialimportance that the sealings fit as exactly as possible so as to reduceleaking out of fibrous material to a minimum. The fibrous suspension tobe treated in the press apparatus is introduced into thecross-sectionally crescent-shaped interspace 69 suitably from both sidesthereof through a conduit 78 opening through the shield plate 70. Theinterspace 69' is closed above the gap 36 or the supply conduit 78 bymeans of a partition wall 80. Since the gap 36 varies in size thepartition wall 80 must be capable of performing its sealing function inspite of the varying spacing between the cylindrical screen surfaces ofthe cylinder and the drum. This is accomplished in the embodiments shownby tongues 82 made of rubber or Teflon and engaging the cylindricalsurfaces in consideration.

The drum 14 carries on its inner wall a cylindrical screen 84 which mayhe supported by a sleeve 86' which on its inner face is formed with alarge number of peripherally extending shallow grooves 88. Providedaround the sleeve 86 is a strong jacket 90 formed with circumferentiallyextending flanges 92 supporting the sleeve 86. The inwards projectingflanges 92 are traversed by axial channels 94 and the center portion ofthe jacket 90 is formed with radial apertures 96. The liquid whichpasses through the screen 84 follows the shallow grooves 88 and axialslots 98 each of which connects a plurality of grooves with the outerface of the sleeve 86. Said slots 98 are arranged, as will be seen fromFIG. 1, in groups displaced relatively one another both axially andperipherally in order to avoid inappropriate weakening of the sleeve.The expelled liquid continues its flow through the channels 94 to thedischarge apertures 96. Located at the base part of the press is acollecting trough 100 with a drain 102 for recovery of the liquid to betreated further.

The inner cylinder 12 may be formed with surfaces of substantially thesame kind as those of the drum 14 for separating and collecting theexpelled liquid. The cylindrical inner Wall of the cylinder 12 is thusformed of a screen 104 supported by a sleeve 106, which latter isprovided with a great number of shallow grooves 108 communicating withthe interior of the sleeve by means of groups of axial slots 110. Saidslots open into pockets 1'12 limited by mutually parallel walls orpartitions 114 and radially projecting walls or partitions 116 havingfoot-like prolongations .118. In the embodiments shown the number ofpockets 112 around the circumference is eight but may, of course, be anyother suitable number. The individual pockets are thus separated fromone another both in the axial and in the peripheral directions. Adjacentthe hub they communicate through radial bores 120 with an axial innerbore 122 extending through the cylinder and its two journals 16 and 18.The bore 122 may be subdivided by means of an elongated partition member123 participating in the rotation and divided into eight channels onefor each row of pockets 112 so as to prevent any overflow of liquidbetween the various radial rows of pockets. To one or both journals astationary drain conduit 124 opening into the trough 100 is connected.

The suspension which in the case envisaged is assumed to consist of pulpfibers contained in a liquid containing chemicals in a concentration ofsolid particles of about 5 to 15 percent, for example, is introducedthrough the conduit or conduits 78 into the interspace 69 between thecylinder 12 and the drum 14. If desired the supply may be effected undersuperatmospheric pressure such as several kilograms per squarecentimeter, for example. While the cylinder and the drum slowly rotatein the direction indicated by the arrow 34, the liquid will be expressedthrough the two screens 84 and 104. The perforations of the screen mayhave so large diameter as one or several millimeters, since pulp fibersimmediately deposit over the perforations during the initial part of thepressing operation and thereby form a kind of filter. During themovement of the two screens in counter-clockwise direction the spacingbetween them is reduced and more and more liquid is expelled. In the nip38 the compression and the pressure force reach their maximum value andthe consistency of the pulp may have been concentrated to about 45 to 50percent. The liquid expelled through the screen 84 escapes through theapertures 96 to the drain 102. The liquid which is separated through theinner screen 104 is during the passage between the gap and nip forcedinwards through the pockets 112 to the branch channels of the bore 122and escapes through the conduit or conduits 124 to the drain 102. Due tothe specific form of the pockets 112 the liquid during the passage ofthe pockets through the upper part of the press is prevented fromreturning to the dried pulp substance fed to said upper part. Said pulpsubstance is removed from the press by means of a screw 126. Arrangedaround the screw is a doctor plate 128 the edges of which scrape alongthe screens 84 and 104 to remove fibrous substance deposited thereon.

As in particular will be evident from FIG. 2, the nip is located abovethe level of the horizontal middle plane of the press and on the sidewhere the cylindrical screens during their rotation move upwardly. Thenip 38 may form an angle of about 30 with the horizontal plane viewedfrom the shaft of the cylinder 12. By this arrangement it is ensuredthat the expelled liquid by its own gravity is prevented from returningto the concentrated solid substance.

As already mentioned, the pressure is produced by hydraulic means. Eachof the bearings 20, 21 supporting the inner cylinder 12 is subjected tothe action of a hydraulic servo-motor denoted by 130 and 132,respectively (see FIGS. 3 and 4). Each of said servo-motors has acylinder within which a plunger denoted by 134 and 136, respectively, isdisplaceable. The plunger may house a central tap 138 having somecapacity of automatic re-adjustment relative said plunger. Oil issupplied to the plunger chamber of the servo-motors by conduits 140 and142, respectively. For removal of leakage oil an annular groove 144 anda drain 146 may be provided in the casing of the servo-motor.

It is of great importance that the pressure acting on the cylinder 12 isautomatically adjusted according to the distribution of the material tobe separated within the interspace 69 in the axial direction thereof.If, for example, when starting the press more material has collected atone side of the interspace than at its other side, the cylinder at thatside, which has received less material, will have a tendency to greaterdisplacement than the other side. If thus the cylinder 12 is loaded moreat its right side than at its left side viewed in the plane of FIG. 4,the plunger 136 will immediately meet a strong counter-pressure whilethe plunger 134 will have a tendency to displace the cylinder, so as totend to cause an inclination thereof. Such inclination must, however, becounter-acted inter alia because the sealing between the shield plates70 and the cylinder would be impaired.

As illustrated in FIG. 4 an adjusting valve 146a is provided. The valvehas a body generally denoted by 148 with portions adapted to seal withsliding fit against cyli-ndric faces provided in the valve house andother portions having a minor diameter and separating the firstmentionedbody portions from one another. The internal face of the valve casingalso has alternating portions with larger and minor diameter. From asump 150 oil is fed by a pump 152 under constant pressure firstlythrough a conduit 153 to a chamber 154 inthe valve and secondly througha conduit 156 with branch conduits 158 and 160 to the pressure chambersof two servo-motors 162 and 164, respectively. Within said servo-motorspistons 166 and 168 are operative to actuate the bearings 20 and 21,respectively, but in a direction opposite to the direction of actuationby the plungers 134 and 136. Since the pistons 166, 168 have a smallerdiameter than the plungers 134, 136 the force by which thefirst-mentioned pistons actuate the cylinder 12 is less than the forceexerted by the last-mentioned plungers as long as both the pistons andthe plungers are subjected to the same specific oil pressure. Laterallyof the central chamber 154 the valve casing is formed with chambers 170,172, 174 and 176, which all are in connection with a conduit system 178,180 which in turn is in open communication with the sump 150 for whichreason no pressure can be built up in said chambers. A spring member 182tends to push the body 148 to the left in the plane of FIG. 4. Aprolongation 184 of the body 148 projects from the casing of the valveand supports one end of a lever arm 186 mounted pivotally rotatableabout a journal 188 formed on a bar 190. The other end of said lever arm186 is articulated with one end of a bar 194, the other end of which isinserted into the block 65 of the bearing 21. Another lever arm 196 ispivotably mounted in the stationary point 198 and by its one endarticulated with the bar 190 and by its other end with a bar 200extending to the block 64 of the other bearing 20.

In the position of the body 148 illustrated in FIG. 4 pressure fluidsuch as oil is supplied through the two conduits 140 and 142 under fullpressure with which pressure thus the two plungers 134 and 136 uniformlyactuate the cylinder 12 and which pressure may be of an order ofmagnitude of 50 tons in both servo-motors. If, however, for any reasonthe supply of fibrous substance to the right side of the cylinder 12becomes less than the supply to the left side, the plunger 136 will meetless resistance and consequently displace the block 65 over a largerdistance than the plunger 134 displaces the other block 64. The cylinder12 will thus take an inclined position. This will, however, result inthe fact that the bar 194 moves upwards and the lever arm 186 is turnedcounter-clockwise about the bearing point 188 and the body 148 is drawntowards the left viewed in the plane of FIG. 4. By this movement thatpart of the chamber 154 which communicates with the conduit 142 will bethrottled and possibly totally sealed from the inlet 153 and in acorresponding degree connected with the pressureless drain 180. Theforce produced by the counter acting small servo-motor piston 168 willnow become dominating and cause the block 65 to be pushed back and theinterspace 69 readjusted to uniform width. If on the other hand theplunger 134 tends to displace the left block 64 so as to cause aninclined position of the cylinder 12, the arm 200 is broughtautomatically to move upwards and the lever arm 196 to turn in aclock-wise direction whereby the bar 190 is pushed to the right andentrains the lever arm 186 which is prevented by the bar 194 fromrotation about the tap 188. As a consequence the body 148 will be forcedto the right and the conduit 140 will now be opened to partly orcompletely reduced pressure, which allows the little piston 166 to pushthe block 64 back and thereby to eliminate the tendency of imparting aninclination to the cylinder 12.

Due to the feature that the roller 12 is displaceable in the horizontalplane in accordance with the description given hereinbefore and that thenip 38 is angularly displaced upwardly the further advantage is obtainedthat a larger pressure component is obtained than would be available ifthe nip would coincide with the plane of attack of the pressure. Sincethe driving sprocket is located below the bearings 20, 21 the cylinder12 is capable of performing its displacement movements in the horizontaldirection without any disturbing influence on the transfer of thedriving force through the chain 58. The sprocket 60 will only swing overa minor angle in both directions from a central position whichdisplacement is tolerable without any disadvantage.

The embodiment according to FIG. 5 differs from the preceding onesubstantially by the feature that the central bore 122 houses astationary slide 202 having substantially semi-spherical cross-section.The bore 122 is preferably formed in a shaft 204 rigidly connected withthe hub of the cylinder 12. Provided in the rear parts of the pockets112 seen in the direction of rotation are channels or tubes 206extending outwardly towards the screen 104 and communicating by means ofchannels 208 with the interior of the bore 122 when in a positiondirectly in front of the interspace 69 and thus uncovered by the slide202. The expelled liquid is carried away through the tubes 206 possiblyby means of a vacuum produced in the'bore 122. When a channel 208 duringthe rotation is covered by the slide 202, the channel is closed and atthe same time the outer opening of the tube 206 arrives at or adjacentthe nip 38. The pockets 112 communicate through channels 210, 212 formedin the hub of the cylinder 12 and the shaft 204, respectively, with theinterior of the slide 202 when the pockets pass through the upper partof the press where the removal of the compressed solid material iseffected. It is obvious that the channels 208 and the channels 210, 212are axially displaced in relationship to one another.

It may happen that solid material particles remaining in the aperturesof the screen may act as bars for the passage of the liquid. In order tocounter-act this effect a cleaning may be accomplished by conducting agas stream, preferably air under pressure or steam, through the holes 96when these move past the nip and before they have passed the horizontalplane. The space between the sleeve 86 and the outer wall of the drumshould in such a structure be provided with partition walls subdividingsaid space into separate pockets, seen in the axial direction. Similarmeans may be provided for cleaning of the holes in the screen of theinner cylinder. In this case the pressure medium is introduced through aslide provided in the central bore of the inner cylinder which mayresemble the member 202 though this latter has two passages.

While several embodiments of the invention have been shown :anddescribed, it is to be understood that this is for purpose ofillustration only and that the invention is not to be limited thereby,but its scope is to be determined by the appended claims.

What I claim is:

l. A press for separating material suspended in a liquid and whichmaterial is of a fibrous nature, comprising a pair of drum-like pressmembers, one of which is disposed within the other land between whichthe suspens-ion is introduced, means for rotating said press members,said press members being on horizontal axes, with one of the pressmembers being arranged eccentrically within the other to thereby providespacing of crescent formation between them, said spacing at itsnarrowest point providing for a material-compressing nip, the two pressmembers having foraminous portions through which separation of theliquid takes place, and hydraulically-operated servomotors located onopposite sides of the inner press member for urging the inner pressmember toward the outer press member with a force having a radialdirection tending to be exerted below the point where the spacingbetween the press members is narrowest, the inner press member beingradially displaceable relative to the outer press member in a horizontaldirection in order to adjust the size of the nip in the spacing betweenthem, bearings at each side of the inner .press member, and twoadditional hydraulicallyoperated servo motors acting in opposition tothe firstmentioned servo motors to obtain a nip between the pressmembers of the same Width for the length of the press members, saidadditional motors being arranged at the sides of the inner press memberto individually actuate said bearings, the first-mentioned motors beingof a larger capacity than the last-mentioned additional motors.

2. A press constructed according to claim 1 and characterised by thefact that control members are provided to co-operate with the innerpress member in a manner to distribute the pressure in the axialextension of space between the press members so that the one of thefirstmentioned servo motors which displaces its end of the inner pressmember more than the other is partly or totally unloaded.

3. A press constructed according to claim 1 and characterised by thefact that the inner press member has the shape of a cylinder whose outerperiphery is covered by a fonaminous member which is internally axiallysub-divided into a plurality of individually separated pockets, a centerduct in the inner press member and the pockets being in communicationwith said duct.

4. A press constructed according to claim 3, and characterised by thefact that the outer press member consists of a drum, the inner side ofwhich is covered with a screen member outside of which are arrangedmutually communicating channels, a jacket extending around the outerdrum and provided with reinforcing flanges, and the channels beingarranged in said jacket.

References Cited in the file of this patent UNITED STATES PATENTS2,374,046 Stocom Apr. 17, 1945 2,682,832 Lohre et a1. July 6, 19542,715,871 Dosne et a1 Aug. 23, 1955 2,764,869 Scherr Oct. 2, 19562,795,184 Graham June 11, 1957 2,978,976 Hazel-ton et al Apr. 11, 19613,000,294 Lowe et a1. Sept. 19, 1961 FOREIGN PATENTS 217,919 AustraliaOct. 8, 1958

1. A PRESS FOR SEPARATING MATERIAL SUSPENDED IN A LIQUID AND WHICHMATERIAL IS OF A FIBROUS NATURE, COMPRISING A PAIR OF DRUM-LIKE PRESSMEMBERS, ONE OF WHICH IS DISPOSED WITHIN THE OTHER AND BETWEEN WHICH THESUSPENSION IS INTRODUCED, MEANS FOR ROTATING SAID PRESS MEMBERS, SAIDPRESS MEMBERS BEING ON HORIZONTAL AXES, WITH ONE OF THE PRESS MEMBERSBEING ARRANGED ECCENTRICALLY WITHIN THE OTHER TO THEREBY PROVIDE SPACINGOF CRESCENT FORMATION BETWEEN THEM, SAID SPACING AT ITS NARROWEST POINTPROVIDING FOR A MATERIAL-COMPRESSING NIP, THE TWO PRESS MEMBERS HAVINGFORAMINOUS PORTIONS THROUGH WHICH SEPARATION OF THE LIQUID TAKES PLACE,AND HYDRAULICALLY-OPERATED SERVOMOTORS LOCATED ON OPPOSITE SIDES OF THEINNER PRESS MEMBER FOR URGING THE INNER PRESS MEMBER TOWARD THE OUTERPRESS MEMBER WITH A FORCE HAVING A RADIAL DIRECTION TENDING TO BEEXERTED BELOW THE POINT WHERE THE SPACING BETWEEN THE PRESS MEMBERS